NAIROBI, Aug 28 (Reuters) - African Islamists may be emboldened by the Islamic State's gains in the Middle East, and local security services need to cooperate to counter the continent's militants, African intelligence officials heard on Thursday.

African Islamist rebels like Nigeria's Boko Haram have not made as dramatic an advance as Islamic State, which controls a swathe of Syria and Iraq. But they have launched attacks across Africa, from Niger, Mali and Nigeria in the west to Somalia and Kenya in the east.

The success of Islamic State could shape the thinking of African Islamists, said Andrew Muzonzini, Zimbabwe's head of external intelligence and a member of the African Union's Committee of Intelligence and Security Services of Africa (CISSA).

"Given (Islamic State's) brutality in pursuit of its cause, it would be prudent for us to brace ourselves for a new cadre-ship of extremist fanatics," Muzonzini said at a CISSA conference in Nairobi.

Islamic State's success may be "the most significant development in the international jihadist discourse" since al Qaeda's attack on United States on Sept. 11, 2001, he said. "Ahead of time, we should seek to understand (the Islamic State) modus operandi if we are to anticipate and predict challenges ahead."

Africa has many Islamist militant groups, which have operated with varying levels of success. Boko Haram controls territory in Nigeria, but holds no strategic towns or major resources. Somalia's al Shabaab has been beaten back in recent years by African Union peacekeepers.

Kenyan Deputy President William Ruto called at the conference for better intelligence sharing between African states to challenge Islamist militants and criminal cartels smuggling arms, drugs and ivory.

"We must match these threats with commensurate imagination and innovative solutions," Ruto said in the Kenyan capital, the site in last September of a bold attack by al Shabaab gunmen on the Westgate shopping mall, an assault that left 67 people dead. (Reporting by Drazen Jorgic; Editing by Larry King)